Opera and WebKit passed the first two stages of the ACID 3 test shortly after its release in March. These measure the actual tests themselves (100/100), plus the pixel-perfect appearance of the page. The final stage, “smooth animation,” has been a more difficult task. The passing version of WebKit does render for me without hiccups, but there appears to be no solid definition of “smooth.”

On the official release browsers I have access to, the highest score was a 75, for Safari 3.1.2. Firefox 3.0.2 was close with a 71.

Shortly after WebKit and Opera passed the test, Mozilla’s Mike Shaver said Firefox would not scramble to pass the tests and that ACID 3 was a missed opportunity:

“Acid 3 could have had a tremendous positive effect on the web, representing the next target for the web platform, and helping developers prioritize work in such a way as to maximize the aggregate capabilities of the web. Instead, it feels like a puzzle game, and I can easily imagine the developers of the web’s proprietary competitors chuckling about the hundreds of developer-hours that have gone into adding another way to iterate over nodes, or twiddling internal APIs to special case a testing font.”

Regardless, some within the Firefox community appear to be working on it, reporting scores in the mid-90s earlier this month.